Composite article



Oct. 11, 1932. G, A, GRQS 1,881,520

COMPOSITE ARTICLE Filed Feb. 16, 1929 #Waff/0fl 60s/We A fas Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE CUsTAvE ADOLPII GROS, or WESTERN SPRINGS, ILLINOIS, ASSIGNOR To WESTERN ELEC- TRIC COMPANY, INCORPORATED, or NEW YORK. N. Y., .a CORPORATION or NEW YORK COMPOSITE ARTICLE Application filed Ilebl'uaryy 16, 1929. .Serial No. 340,626;

This invention relates to composite articles.

This invention has been found particularly useful for making terminal banks of large size involving a large number of terminals which form a part of an automatic selector switch of a type used in dial telephone eX- change systems. Terminal banks of this character often include more than three hundred rows of multiple contacts and in some instances a method has been practiced in which strips of considerable length of electrical conducting material and fibrous material impregnated with an insulating and bonding material have been superimposed on each other. The fibrous strips are wider and longerv than the conducting strips and are provided with perforations which are aligned with certain perforations provided in the conducting strips and -through which are threaded pins used'in the assembling of the strips. Subsequently other pins are threaded into the perforations for the purpose of mounting the finished bank upon a metal supporting frame. The conducting strips are provided with projections which serve as terminals and contacts and thewhole assembly forms a terminal bank of the arrangement shown in a patent to Dixon, No.

' 1,127,741, February 9, 1915.

The Objects of this invention are to pro* vide a rigid composite article wherein the elements thereof are predeterminedly spaced and integrally united and its vmethod of manufacture.

In orderto attain these objects in accordance with the features of this invention as applied to terminal banks, a plurality of completely ycured phenol fibre strips are formed accurately to a desired thickness, which may be slightly more or less than a spacing between the conducting strips, but in the aggregate the thickness of a plurality of the strips being less than the aggregate of a similar number of spaces therebetween. The term phenol fibre strips will be described inv detail hereinafter. The phenol fibre strips are then exteriorly treated with a phenolic condensation product such as phenolic varnish which is then partially cured. A plurality Of the treated strips are then alternately superimposed with a plurality of perforated conducting strips upon aligning pins threaded through certain perforations in the conducting strips and, correspondingly spaced perforations inthe phenol fibre strips, the latter perforations being provided primarily for assembling the bank and for mounting the finished bank upon its supporting frame. kThe superimposed strips are then mounted on a fixture with the aligning pins and subjected to the action of heat and pressure to an approximation of a final desfred dimension, to force the partially cured phenolic varnish into the unused perforations and over the edges of the conducting strips to interconnect alternate phenol fibre strips, to interlock the latter strips With the conducting strips and to form a bond between the parallel opposed surfaces of the strips, the heat being continued without ade ditional pressure until the phenolic varnish is curved. Thereafter the superimposed strips arepermitted to cool and simultaneously therewith and during the shrinkage which occurs during the cooling'the structure is'subjected to pressure to produce a superimposed structure of an infusible and insoluble character and a final desired dimension with the conducting strips uniformly spaced.

Other Objects and advantages of this in- Vention will more fully appear from the following detailed description taken in connection f with the accompanying drawing, wherein Fig. 1 is a side View of a fixture for assembling the phenolV fibre and conducting strips of a terminal bank embodying the features of this invention in superimposed f predetermined relation in practicing the method of this invention;

Fig. 2 is an end view thereof;

Fig. 3 is a fragmentary side view of a ter-l minal bank produced according tothe method of this invention;

Fig. l is a top plan view thereof;

Fig. 5 is an enlarged fragmentary vertical Sectional view taken on the line 5 5 of Fig. 3, and

Fig. 6 is an enlarged fragmentary' vertical sectional view taken on the line 6-6 of Fig. 4.

eferring now to the drawing in detail wherein like reference numerals refer to similar parts throughout the drawing, the method of this invention may bev carried out by first providing aplurality of strips 10 each of which comprises laminations of fibrous material, such as paper, cloth, or fabric cut to a suitable size, each lamination thereof being impregnated with a phenolic condensation product and the whole united and completely cured by the application of heat and pressure to produce a strip of an incompressible, infusible and insoluble character. The strips 1'0"(:111:` from the cured'y phenol sheets are then formed by' grinding or otherwise to an accurate-desired thickness which may be slightlfy more orless thanthe spacing between electricalconducting strips 11, which also are cut toa suitable size. In actual practice the aggrega-tel'thickness of a plurality of the strips 10 should" be less than the aggregate of a similar number of' spaces therebetween, the purpose oflwhich will be described shortly. The strips 10 afterl being ground to the desired thickness arey exteriorly treated or coated by spraying or dippingthe strips in a bath of phenolic varnish or other phenolic condensation product, the varnish being precured by insertingv the strips in an oven or other suitable means. Referring particularly to Figs. 4i andl 6, a plurality of perforations 12 are formed inthe conducting strips 11 throughvout their length which reduces thev area of the metal surface and thus effectively eliminates or at least greatly lowers the mutual capacity between the insulating phenol libre strips 10. Certain ofthe perforations 12are aligned with perforations 13 of asimilar size formedin: the phenol fibre strips 10 which are used in the assembling and aligning of the stripsy andi subsequently in the mounting of the finished terminal bank on a supporting frame. The perforations 12 of the conducting strips 11 which are not used for assembling'purposes .as hereinbefore described also serve another purpose in addition to that herein mentioned, which will be made apparent hereinafter. As clearly indicated in Figs: 3 and 4 the phenol fibre strips 10 are Wider and longer than the conducting strips 11 with the exception of proj ectingterminals and contacts 14 and 15, respectively, thereon, thus minimizing, due to the projecting portions of the phenol fibre strips 10,A the possibility of a short circuit between the edges of the conducting` stripsy 11.

Therstrips 10 and 11 are assembled alternately in superimposed rela-tionv upon a fixture (Figs. 1 and 2) comprising a base 18 having aplurality'of vertically disposed removable metal aligning pins 19 mounted thereon, only two of which are shown in Fig. 1;, the pins 19. being slightly less in diameter than the cooperating perforations 12 and 13 of the strips 11 and 10, respectively.

When the desired number of the strips 10 and 11 have been alternately superimposed upon the pins 19 of the fixture they are transferred from the fixture, still mounted on the pins, and between compressing members of a suitable fixture (not shown) by entering the ends of the pins 19 in suitable apertures provided in the compressing mem bers. The aligned perforations 12 and 13 through the superimposed strips 11 and 10, respectively, used in assembling the strips upon the pins 19 are also used in the mounting of the bank upon a metal supporting frame (not shown) by bolts or rods 22, one of which is indicated in Figs. 4 and 5, passingtherethrough, provided with an insulatingv bushing, the diameter of which is the same as the perforations. The insulating bushings in the completed bank provide a wall of insulating material between the conducting strips 11 and the bolts or rods 22 used to secure the bank upon its frame.

Upon'the superimposed strips 10 and 11 being mounted between the compressing members in the compressing fixture (not shown) and subjected to sufiicient pressure to cause the strips to be firmly clamped, the fixture is inserted into a. suitable oven (not shown) or other heating means, whereby the heat preferably will be applied at right angles to the line of compression to provide for a uniform softening of the uncured phenolic varnish coating on each phenol fibre strip 10. lVhen the coating has been softened sufficiently the compressing fixture is withdrawn from the heating means and immediately the superimposed strips 10 and 11 are subjected to additional pressure until an approximation of a final desired height of the superimposed strips is obtained, for example, within one quarter inch of their final height. This last compression step provides a uniform spacing of the strips 10 and 11. Preferably, the strips 10 and 11 may be subjected to the simultaneous action of heat and pressure by a suitable combined heating and compressing means (not shown). During this last mentioned compression of the strips 10 and 11 the excess softened phenolic varnish or other condensation product it will be apparent will bev forced over the longitudinally and laterally extending edges of the electrical conducting strips 11 upon each side thereof, from the abutting phenol fibre strips 10, as is clearly indicated in Fig. 5, to form in most instances continuous interconnections in the form of beads 32 of phenolic varnish between alternate phenol fibre strips 10 around each conducting strip 11, except the projecting contact portions 15. The softened phenolic varnish is also forced into the unused perforations 12 of the conducting strips 11 in the form of dowels 33 (Fig. 6) which also serves to interconnect alternate phenol fibre strips 10 and interlock the latter strips with the conducting strips 11.

The phenolic varnish between the parallel opposed surfaces of the strips 10 and ll acts as a cushion and filler to compensate for variations in the thickness of the ground phenol fibre strips l0 or of the conducting strips ll in addition to a bonding agent therebetween, the net result being that small variations in the thickness of the strips which would produce a deleterious accumulative effect in the overall dimensions of the finished structure is eliminated. Upon the phenolic varnish being completely cured the varnish between the parallel opposed surfaces of the strips lO and ll will act to firmly bond together the strips, and the varnish which is forced over the edges of the conducting strips 1l and into the perforations l2 thereof will serve as a very effective interconnection between the phenol fibre strips 10 and an interlock for the phenol fibre strips l0 with the conducting strips ll, as well as serving to improve the insulation resistance of the phenol fibre strips l0. lVhen the height of the superimposed strips 10 and ll is within one-quarter inch of their final height as hereinbefore described the heating or curing step is con tinued without increasing the pressure until the phenolic varnish coating is completely cured and thereafter is withdrawn from the. heating means and cooled either by room temperature or by suitable means and simultaneously therewith and during the shrinkage which occurs during the cooling the superimposed strips are subjected to pressure to bring them to a final desired height with the conducting strips 1l predeterminedly spaced and producing a terminal bank of an infusible and insoluble character. It is to be understood that during the application of heat and pressure to the stacked interleaved phenol fibre strips 10 individually coated with phenolic varnish and the metal conducting strips 11 no change in the individual thickness of the strips 10 occurs, since each of the strips as hereinbefore described has been completely cured before assemblage with the strips 11 into an incompressible, infusible and insoluble strip.

Since the compressing and heating operations may be performed in any convenient apparatus a disclosure of specific apparatus for accomplishing these operations is not believed necessary to a full understanding of this invention and have been omitted.

While the invention has been disclosed and described in connection with a particular article, it will be understood that the invention is capable of application to other types of articles and is only limited by the scope of the appended claims.

What is claimed is:

l. A composite article comprising a plusurfaces of the Ebre sheets, the whole superimposed structure formed into an article of an infusible and insoluble character, the first mentioned sheets being greater in extent than the latter sheets, and dowels and beads of "cured condensation product extending into the perforations from the fibre sheets and over the edges of the conducting sheets respectively to interlock and interconnect the strips.

2. A terminal bank for telephone exchange systems comprising alternately superimposed completely cured phenol fibre strips formed to an accurate thickness with a surface coating of a phenolic condensation product and electrical conducting strips having projecting contacting lugs, the whole superimposed structure formed into an infusible and insoluble terminal bank with the conducting strips uniformly spaced, the phenol fibre strips being of greater area than the conducting strips but narrower than the projecting lugs thereof, and beads of phenolic condensation product extending around the conducting strips to interconnect alternate fibre strips.

3. A terminal bank for telephone exchange systems formed of alternately superimposed accurately pre-formed, completely pre-cured phenol fibre and metal elements, one of the elements having a cured surface coating of a phenolic condensation product, the whole superimposed structure formed into a bank of an infusible and insoluble character.

In witness whereof, I hereunto subscribe my name this 31st day of January A. D.,

GUSTAVE ADOLPH GROS. 

